0f3cadcc3e
These have no effect in Python 3.x, they are the default. Enabling them in Python 2.x, enabling them in Python 2.x allows single source compatiblity.
60 lines
1.5 KiB
Python
60 lines
1.5 KiB
Python
#!/usr/bin/env python2
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# Example parser: Base64, syntax only.
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#
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# Demonstrates how to construct a Hammer parser that recognizes valid Base64
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# sequences.
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#
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# Note that no semantic evaluation of the sequence is performed, i.e. the
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# byte sequence being represented is not returned, or determined. See
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# base64_sem1.py and base64_sem2.py for examples how to attach appropriate
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# semantic actions to the grammar.
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from __future__ import absolute_import, division, print_function
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import sys
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import hammer as h
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def init_parser():
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# CORE
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digit = h.ch_range(0x30, 0x39)
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alpha = h.choice(h.ch_range(0x41, 0x5a), h.ch_range(0x61, 0x7a))
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# AUX.
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plus = h.ch('+')
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slash = h.ch('/')
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equals = h.ch('=')
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bsfdig = h.choice(alpha, digit, plus, slash)
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bsfdig_4bit = h.in_('AEIMQUYcgkosw048')
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bsfdig_2bit = h.in_('AQgw')
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base64_3 = h.repeat_n(bsfdig, 4)
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base64_2 = h.sequence(bsfdig, bsfdig, bsfdig_4bit, equals)
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base64_1 = h.sequence(bsfdig, bsfdig_2bit, equals, equals)
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base64 = h.sequence(h.many(base64_3),
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h.optional(h.choice(base64_2, base64_1)))
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return h.sequence(h.whitespace(base64), h.whitespace(h.end_p()))
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def main():
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document = init_parser()
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s = sys.stdin.read()
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inputsize = len(s)
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print('inputsize=%i' % inputsize, file=sys.stderr)
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print('input=%s' % s, file=sys.stderr, end='')
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result = document.parse(s)
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if result:
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#print('parsed=%i bytes', result.bit_length/8, file=sys.stderr)
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print(result)
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if __name__ == '__main__':
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import sys
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main()
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